Strengthened fibre fleeces

ABSTRACT

The object of the invention is a strengthened fibre fleece from staple fibres containing as strengthening agent a copolymer based on acrylic and/or methacrylic acid esters and styrene. The copolymer contains additionally in copolymerised form a monomer having nonconjugated carbon double bonds, acrylic acid and methacrylic acid, and methacrylamido-N-methylolmethylether. In a process for producing the strengthened fibre fleece, the fibre fleece is impregnated with an aqueous dispersion of the copolymers and subsequently dried at temperatures between 60* and 130*C.

e'itzel et a1. 1 1 1973 [54] STRENGTHENED FIBRE FLEECES 3,095,320 6/19 63 Leitner ll7/l6l x 1 1 weiml; flellmmsmegler, $32133 $11333 $553152.fffiiii...........13i3::.T347353 both of L v rk Germany 3,231,533 l/l966 Garrett et al. 117/140 [73] Assignee: Bayer Aktiengesellschaft,

Leverkusen, Germany [22] Filed: Mar. 8, 1971 [21] Appl. No.: 122,145

[30] Foreign Application Priority Data Mar. 14, 1970 Germany P 20 12 287.6

[52] 11.8. (1117/1410 A, 117/138.8 F, l17/138.8 N,

117/145, 117/161 UT, 117/161 UN [51] Int. Cl B321) 27/12, C09d 3/80 [58] Field of Search 117/161UZ, 161 UD, 117/161 UT, l6l UN, 161 UH, 138.8 F,

138.8 N, 145, 161 UC, 140 A; 260/29.7 T,

Abrams et a1. 260/29.7

EQBEEQE BATENISQRAPZLL QNS 747,328 1l/1966 Canada ll7/l6l 1,193,080 5/1970 Great Britain 117/161 1,277,191 9/1968 Germany 117/161 Primary Examiner-William D. Martin Assistant ExaminerHarry J. Gwinnel Att0rneyPlumley & Tyner ABSTRACT 3 Claims, No Drawings 1 STRENGTHENED FIBRE FLEECIES The invention relates to strengthened fibre fleeces and a process for their production in which the fibre fleeces are treated with aqueous dispersions.

It is known to use aqueous dispersions of homopolymers and copolymers of monomers having one or more polymerisable double bonds for producing bonded fibre fleeces. it is well known that polymers into which diolefines have been polymerised are not resistant to ageing and must be stabilized. On the other hand, these polymers can be cross-linked by curing at the double bonds which are still free. Another possibility of establishing a transverse connection between the polymer chains by cross-linking consists in incorporating polymerisable compounds which contain reactive groups into the polymer chain and causing them to react by a supply of energy such as heat or radiation.

These reactive groups may be either in their original form or in a masked form and in all cases react in their original form. N-Methylolacrylamide and N- methylolmethyl ether of methacrylic acid amide may be given as examples. The advantage of these polymers which have been cross-linked in this way and which have been prepared without the use of monomers which contain several double bonds is that they give rise to highly cross-linked products which impart to the fibre fleeces a satisfactory resistance to cleaning processes.

This cross-linking must be carried out at relatively high temperatures at which delicate fibres, such as wool fibres, are liable to be damaged. On the other hand, it has often been observed that cross-linking is not completed owing to technical deficiencies in the drying assemblies, and the materials obtained are not resistant, for example, to chemical cleaning processes.

There is a need to overcome these difficulties and to enable the cross-linking process to be completed at lower temperatures. It is known that the degree of cross-linking of the polymer can be increased from the start by incorporating copolymerisable esters of a glycol such as butanediol with (meth)acrylic acid and in addition incorporating N-methylol(meth)acrylamide, fleeces which are very resistant to detergents and solvents being thereby obtained (see DAS No. 1,277,191).

It is an object of the invention to make the conditions required for cross-linking considerably milder without any loss of resistance to detergents and solvents in the fleeces by incorporating a combination of cross-linking monomers which have two polymerisable double bonds and methacrylamido-N-methylolmethylether and acrylic acid/methacrylic acid.

This invention therefore relates to strengthened fibre fleeces obtained from natural, synthetic or mineral staple fibres or from mixtures of these staple fibres containing as strengthening agent a copolymer based on acrylic and/or methacrylic acid esters and styrene, which copolymer contains 0.2 to 2 per cent by weight of a monomer having two isolated polymerisable carbon double bonds and 0.1 to 5 percent by weight of methacrylamide-N-rnethylolmethylether and l to 10 percent by weight of acrylic acid and methacrylic acid in a polymerised form, the proportion of acrylic acid to methacrylic acid being between 1:10 and 10:1 and the proportion of monomer which has two carbon double 2 bonds to acrylic acid and methacrylic acid being between l:20 and 4:1.

Another object of the invention is a process for strengthening fibre fleeces in which aqueous dispersions of acrylic and/or methacrylic acid esters and styrene are used as binders, these dispersions containing 0.2 to 2 percent by weight of compounds which have two polymerisable double bonds, 0.1 to 5 percent by weight of methacrylamidoN-methylolmethylether and l to 10 percent by weight of acrylic acid and methacrylic acid, the percentages by weight being based on the total amount of polymer.

The copolymers mentioned above are copolymers which contain a major amount of acrylic and/or methacrylic acid esters incorporated by polymerisation. Acrylic and methacrylic acid esters of alcohols which contain 1 to 8 carbon atoms are especially suitable, for example the butyl esters, isobutyl esters, methyl esters, ethyl esters, propyl esters, hexyl esters and ethyl hexyl esters. The copolymers for use according to the inven- -tion preferably also contain 1 to 60 percent by weight of styrene, based on the total weight of polymer. The copolymers may also contain up to 15 percent by weight, based on the total polymer, of compounds into which a copolymerisable double bond has been polymerised butwhich are not identical with the compounds mentioned above. Examples of these are the nitriles and amides of acrylic and methacrylic acid, vinyl ether, vinyl chloride and vinylidene chloride.

0.2 to 2 percent by weight, based on the total polymer, of a compound which has two nonconjugated polymerisable carbon double bonds are also incorporated by polymerisation. Especially suitable compounds of this type are the esters of acrylic and/or methacrylic acid with bifunctional alcohols such as ethylene glycol and butane-1,4-diol. Vinyl esters of acrylic and methacrylic acid are also suitable. Other esters which contain two polymerisable double bonds, such as divinyl or diallyl esters of dicarboxylic acids and allyl or methallyl esters of acrylic and methacrylic acid and, for example, divinylbenzene, its derivatives and substitution products and amide derivatives of ethylenically unsaturated carboxylic acids, such as methylene bisacrylamide, are also suitable.

The dispersions are prepared in the usual manner but preferably with a maximum of 1 percent by weight of emulsifier, based on the total weight of the copolymer. The following are examples of suitable emulsifiers: Higher alkylsulphonates, acidic sulphuric acid esters of fatty alcohols, alkylarylsulphonates, sulphonated castor oil, sulphosuccinic acid esters, watersoluble reaction products of ethylene oxide and long chained fatty alcohols or phenols, water-soluble salts of sulphonated ethylene oxide adducts and water-soluble salts of optionally alkylated naphthalenesulphonic acids and their condensation products with formaldehyde.

The concentration of the dispersions may vary within wide limits according to the purpose for which they are to be used and the method by which they are to be worked up. The dispersions preferably have a solids content of about 40 to 50 percent by weight.

Fibre fleeces which are strengthened in accordance with the invention may be produced from synthetic or natural fibres, for example cotton fibres, wool fibres, silk fibres or rayon staple fibres or synthetic fibres of polyacrylonitrile, polyesters, polycarbonates, polyamides (Nylon 6, Nylon 66), elastomer fibres or glass fibres or other mineral fibres. The fibre fleeces may also be produced from mixtures of the fibres mentioned above.

Before or at the time of applying the dispersions to longer have sufficient springy elasticity.

The examples given below serve to explain the process of the invention. The parts indicated are in all cases parts by weight.

the fibre fleeces it may frequently be advantageous to 5 add additives to the dispersions, e.g., protective col- Example 1 and Comparison examples A, B and C loids, emulsifiers, wetting agents, substances which A staple fibre fleece having a weight of about 30 g/m prom Prevent g, Substances WhiCh render and produced from regenerated cellulose fibres is imthe materials hydrophobic, y or fillersy pregnated with the 24 percent aqueous dispersion of a cases, it may also be advantageous to add polycondenl0 l r, squeezed ff to reduce the water uptake to sation products, for example of formaldehyde and urea 100 percent (b d o the weight of fibres), dried and o melamine. ctherifiCaIion Products of these 0011- condensed. The resulting fleece has a very pleasant, dry densates. handle and good resistance to dry cleaning and wash- The aqueous dispersions of binder are advantaing. The series of dispersions and binders used showed geously applied to these fleeces by spraying. full bath the variations indicated in column I at a constant impregnation or nip padding. monomer ratio of butyl acrylate (58 parts) to styrene The fibre masses containing the binder are then dried (34 parts) to methacrylamido-Nmethylolmethylether for some time, 3 to 10 minutes being generally suffi- (5 parts). Column [I shows the tear resistances of the cient, a moderate temperature being advantageously fleece and column III the conditions of condensation.

TABLE 1 1 II III Tear resistance (kg. wtJcmfl) Ethylene onden- Methglycol Wet (trisation Acrylic acrylic bis-meth- Wet chloro- 5 min. No. acid acid acrylate Dry (OHIO) ethylene) at 0 C 71 a2 34 110 1 1.05 1.05 0.4 74 3s 47 130 77 34 52 150 70 as 31 110 A 1. 05 1. 05 70 39 130 76 37 40 150 76 a9 42 110 B 3 0 0.4 71 37 49 130 i 66 52 150 68 a0 0 110 o .1 0 0.4 72 3e 130 74 35 48 150 employed at first, generally a temperature of between 60 and 100 C. The binder clearly starts to undergo cross-linking at this stage. The binder is then converted into the insoluble state by further heat treatment, preferably at 80 to 130 C. in principle, heat treatment alone is sufficient to convert the binder into the insoluble state but the heating time can be reduced by the addition of reaction accelerating compounds to the binder, e.g., acids or compounds which give off acids, such as phosphoric acid, p-toluene-sulphonic acid, acetic acid, aluminium chloride, zinc chloride, magnesium chloride, ammonium nitrate or ammonium oxalate.

The strengthened fibre fleeces produced according to the invention have excellent resistance to ageing and do not undergo yellowing. They are very resistant to detergents and solvents.

In practice, it is frequently desirable to produce fleeces which are soft and have a springy elasticity, e.g., for use as interlining for garments. Fleeces which have been produced with the dispersions described here can be worked up especially conveniently because they have the advantage of not producing any difficulties in the making up of the material as has hitherto been the case and moreover the unpleasant sticky handle at the surface of the fleece material no longer occurs. Although this last mentioned disadvantage could be obviated in the known processes by using harder copoly mers, fibre fleeces strengthened in this way then no it will be seen from Example 1 and comparison examples A C that the combination of acrylic acid, methacrylic acid and bifunctional compound imparts optimum properties to the copolymers.

Example 2 Example 3 A fleece of polyester staple fibres (polyethylene glycol terephthalate, staple length 60 mm, 3.3 dtex) which has been produced by crimping and which has a weight of about 200 g/m and a thickness of 5 cm is sprayed on both sides with the mixture described in Example 2 of a dispersion of binder and cationic organic solvents in the proportions indicated (application 20 g of solids on each side, based on the weight of fibres), dried and condensed for one minute at C. This high bulk fleece treated with an antimicrobial finish as in Example 2 can be incorporated in eiderdowns. Such eiderdowns have excellent heat retention and a pleasant handle, can be chemically cleaned without any adverse effect and do not constitute a nutrient medium for bacteria.

We claim:

1. Strengthened fibre fleeces of natural, synthetic or mineral staple fibers or mixtures of such staple fibers;

agent a copolymer comd. 0.1 to 5 percent by weight of methacrylamido-N- methylolmethylether; and

e. l to 10 percent by weight of acrylic acid and methacrylic acid, the proportions of acrylic acid and methacrylic acid being between 1:10 and 10:1 and the proportions of monomer having two nonconjugated polymerizable carbon double bonds to. acrylic acid and methacrylic acid being between 1:20 and 4:1.

2. The product of claim 1 in which the acrylic acid esters and methacrylic acid esters are esters of acrylic and methacrylic acid with aliphatic alcohols which have l to 8 carbon atoms.

3. The product of claim 1 which contains a cationic anti-microbial organic substance. 

2. The product of claim 1 in which the acrylic acid esters and methacrylic acid esters are esters of acrylic and methacrylic acid with aliphatic alcohols which have 1 to 8 carbon atoms.
 3. The product of claim 1 which contains a cationic anti-microbial organic substance. 